How much tg is considered a recurrence of thyroid cancer? How to treat thyroid cancer symptomatically?

In clinical practice, we mainly monitor tumor recurrence through regular follow-up of serological indicators such as thyroid function (Tg, TgAb), neck ultrasound, diagnostic 131I whole-body imaging, etc. If the condition requires, further CT, bone imaging, 18FDG-PET and magnetic resonance imaging (MRI) examinations can be performed. What is the tg level of thyroid cancer recurrence?

For patients who have undergone total thyroidectomy and 131I thyroid ablation, monitoring serum Tg levels is an important method to reflect whether the patient has residual or recurrent tumors. Usually, under the TSH suppression state of oral thyroid hormone, Tg>2ng/mL often indicates the possibility of tumor persistence or metastasis. When thyroid hormone is discontinued to stimulate TSH to rise to a level of>30uIU/ml, serum Tg will usually increase accordingly. At this time, monitoring Tg levels will be more accurate in predicting tumor recurrence. For DTC patients with suspected elevated Tg levels and a high risk of recurrence, further oral small doses of 131I can be considered when thyroid hormone is discontinued for diagnostic 131I whole-body imaging to assist in determining whether there are iodine uptake lesions.

Neck B-ultrasound is the most important imaging examination for evaluating thyroid bed recurrence and regional lymph node metastasis, especially for patients who cannot be diagnosed with recurrence by Tg. Common ultrasound features of suspicious lymph nodes include: irregular lymph node morphology, fusion, unclear cortical-medullary boundary, no central echo, microcalcification, cystic changes, etc. Patients with the above characteristics should undergo further puncture biopsy to clarify the nature of the lesion and further symptomatic treatment.

For patients with persistently high serum Tg levels after 131I treatment but negative imaging examinations (131I whole body imaging and ultrasound), 18FDGPET and PET/CT can be considered to help find local recurrence or metastasis. The sensitivity of PET for detecting thyroid cancer recurrence is 50% to 75%, and the accuracy is related to the serum Tg level. However, due to the high price of PET, it is not suitable for widespread use by Chinese people. Our department also uses relatively low-cost SPECT99mTc-MIBI, somatostatin receptor imaging, and integrin receptor imaging to find recurrence and metastasis that do not take up iodine.